Patent GB-775925-A (GB)
Title: Process for the production of substituted 1.2-diphenyl-3,5-dioxo-pyrazolidines
Filed: 1955-04-12
Abstract: The invention comprises compounds of the formula: <FORM:0775925/IV(b)/1> wherein R represents a hydrocarbon radical with at least two carbon atoms in which methylene groups can be replaced by O or S and a benzene nucleus possibly present can be substituted by halogen, and n is 0 or 1, and their tautomeric forms as well as the salts thereof with inorganic and organic bases, and in particular the compound 1-(p-hydroxy-phenyl)-2-phenyl - 4 - n - butyl - 3.5 - dioxopyrazolidine.  The invention also comprises processes of preparing such compounds by: (1) condensing a malonic ester of the formula: <FORM:0775925/IV(b)/2> wherein R1 is H or R and X is low alkyl or phenyl, in presence of an alkaline condensing agent with a derivative of a hydroxyhydrazobenzene of the formula: <FORM:0775925/IV(b)/3> wherein R1 represents an araliphatic radical which can be split off by hydrogenolysis, in particular benzyl, benzhydryl, a -alkoxyalkyl, or tetrahydropyranyl, Z is hydrogen or acyl which can be easily split off, and n is 0 or 1, to form a compound of the formula: <FORM:0775925/IV(b)/4> or (2) by condensing, in presence of an acid binding agent, a malonic acid halide of the formula: <FORM:0775925/IV(b)/5> wherein Y is chlorine or bromine, with a derivative of a hydroxy-hydrazobenzene of the formula: <FORM:0775925/IV(b)/6> where R11 is R1 or an acyl radical which can be easily split off to form a compound of the formula: <FORM:0775925/IV(b)/7> or (3) first condensing a malonic acid ester halide of the formula: <FORM:0775925/IV(b)/8> in presence of an acid binding agent with a hydroxyhydrazobenzene derivative of formula III to form a malonic acid ester hydrazide of the formula: <FORM:0775925/IV(b)/9> and condensing this in presence of an alkaline condensing agent to form a compound of formula IV.  The radicals R1 and R11 in compounds of formul  IV and VII are then split off to give the free hydroxy compounds, and if R1 is H, radical R is first introduced by reaction with aldehydes or ketones of the formula R0 = 0, wherein R0 is a gem divalent radical corresponding to a primary or secondary radical R but having 1 hydrogen less, and later or simultaneous hydrogenation, which may also remove R1 and R11.  In examples: (1) p-benzyl-oxyhydrazobenzene is reacted in presence of sodium ethoxide with n-butyl malonic acid diethyl ester, to give 1-(p-benzyloxy-phenyl) 2-phenyl - 4 - n - butyl - 3.5 - dioxopyrazolidine, followed by hydrogenation to give 1-(p-hydroxyphenyl) - 2 - phenyl - 4 - n - butyl - 3.5 - dioxopyrazolidine, and reference is made to the use of b  - ethoxyethyl -, cyclopentyl -, and benzyl-malonic acid diethyl ester to give the correspondingly substituted pyrazolidines; (2) m.m1-bis - benzyloxy - hydrazobenzene is reacted with n-butyl malonic acid diethyl ester followed by hydrogenation to give 1.2-bis-(m-hydroxyphenyl) - 4 - n - butyl - 3.5 - dioxopyrazolidine; and reference is made to the use of isopropyl-, n - dodecyl -, and cyclohexyl malonic diethyl ester to give the correspondingly substituted pyrazolidines; (3) p-acetoxyhydrazobenzene is reacted with butyl malonic acid dichloride to give 1 - (p - acetoxy - phenyl) 2 - phenyl - 4 - n-butyl - 3.5 - dioxo - pyrazolidine which is saponified with caustic soda to give 1-(p-hydroxyphenyl) 2-phenyl-4-n-butyl-3.5-dioxo-pyrazolidine, and reference is made to the use of b 1-methylmercapto-ethyl- and b -phenylmercapto-ethyl-malonic acid dichlorides to give the correspondingly substituted pyrazolidines.  The abovementioned hydrazobenzene derivatives may be prepared by reduction of the corresponding azobenzene derivatives.